Hi Ian,

Many thanks for the reply,

Just jacked it up, no bolts / stones / anything stuck in the tyres - all look OK.

Just been for another quick drive, the noise becomes apparent at 20mph. It may still be there below that speed, but not noticable.

From the sound inside the car when driving, and when hanging half out of the car while it's moving! ... the knocking seems to me to be anywhere around 2 feet in front of, or 2 feet behind, the gear stick. Which part that relates to underneath the car i don't know. Do you think from that it's more likely to be drive shaft related ?

Regards,
Dave